Wireless local area networks (WLANs) use infrared (IR) or radio frequency (RF) communications channels to communicate between portable or mobile computer terminals and stationary access points or base stations. These access points are connected by a wired or wireless communication channels to a network infrastructure which connects groups of access points together to from a local area network (LAN), which can include one or more host computers. In turn, the LAN can be connected to another larger network such as the Internet and the World Wide Web (Web). Several protocols, including the IEEE 802.11 standard, “Wireless LAN Medium Access Control (MAC) and Physical Layer (PHY) Specifications” have been designed to standardized WLAN communications. Such standardization is useful for optimizing user requirements, including spatial layout, response time, loading and throughput requirements of the network.
“Roaming” terminals are mobile units that can associate with any access points (AP) associated with a WLAN and seamlessly move from AP to AP. Each roaming terminal analyzes received signals from access points in its vicinity and associates with a single access point. Communication with an access point connects a terminal with the LAN and therefore with external networks such as the Internet. The region around and access point can be referred to as a “cell”. Roaming terminals can move from cell to cell and remain connected to the LAN and any other network to which the roaming terminal has connected.
Typically, these roaming units are passive and client-centered and utilize HTML based server applications. A browser client device, such as a roaming unit, initiates actions generating requests and the server associated with the unit, passively responds to the request. Support of many business applications often requires support of notification actions to contact and instruct users of the roaming terminals who can often be located in isolated areas and out of contact with other people. If someone needs to contact or give instructions to the user, the isolation may prevent the user from being contacted.